Dendrimers are polymers. Dendrimers may be cationic (full generation dendrimers) or anionic (half generation dendrimers). Dendrimers are also known as "starburst" or "star" polymers, due to a characteristic star-like structure. Tomalia reviewed the synthesis, physical properties, and applications of dendrimers. See, e.g., Tomalia et. al, Angew. Chem. Int. Ed. Engl., 29, 138-175, (1990); Tomalia, Aldrichimica Acta, 26, No. 4, pp. 91-101 (1993); Tomalia et al., "Dendritic Polymers" in Encycl. Polym. Sci. & Eng., Index Vol., 2nd ed., Wiley, 1990, pp. 46-92. No mention is made of personal washing compositions containing dendrimers or dendrimers' use as mildness agents.
PCT application WO 88/01178 (Tomalia et al., assigned to the Dow Chemical Company) describes starburst conjugates which are composed of a dendrimer in association with a pharmaceutical material. Dendrimers are employed for targeted delivery of active molecules. Examples of the pharmaceutical materials are drugs or scavenging agents. U.S. Pat. No. 5,338,532 (Tomalia et al.) contains a similar disclosure of dendrimer/active conjugates. The disclosed applications include drug delivery, targeted delivery, complexation with metals for contrast imaging, and complexation with fragrances and dyes for controlled delivery.
A wide variety of personal wash compositions is available to a consumer. Consumers prefer milder (less harsh to the skin) cleansers. Unfortunately, best lathering is obtained from soap or synthetic surfactants which typically do not perform well in clinical mildness tests.
One method of providing skin benefits (e.g., mildness) is through the use of polymeric mildness aids. Cationic polymers, other than dendrimers, have previously been employed as mildness agents in soap bars and liquid cleansing formulations. For instance, U.S. Pat. No. 5,296,159 (Wilson et al.) discloses mild soap bars containing a cationic polymer, such as cationic polysaccharides, cationic copolymers of saccharides and synthetic cationic monomers, and cationic synthetic polymers. Examples of the latter are polyalkylene imine (e.g., polyethylene imine), ethoxy polyalkylene imine, and cationic polyionene (e.g., Mirapol A-15 from Miranol Chem. Co.). U.S. Pat. No. 4,713,236 (Hoover et al.) discloses polymers containing primary pendant amine groups (e.g., polyvinylamine) for imparting good conditioning properties to hair.
Personal wash compositions containing cationic polymeric mildness aids are also disclosed in U.S. Pat. No. 5,322,643 (Schwartz et al.), U.S. Pat. No. 4,820,447 (Medcalf et al.), U.S. Pat. No. 4,985,170 (Dawson et al.), U.S. Pat. No. 4,946,618 (Knochel et al.), U.S. Pat. No. 4,438,095 (Grollier et al, U.S. Pat. No. 4,812,253 (Small et al.), U.S. Pat. No. 4,673,525 (Small et al.), European Patent Application 0 308 190 (Procter & Gamble), European Patent Application No. 0 308 189 (Procter & Gamble), and PCT Application WO 94/03151 (Unilever).
Unfortunately, cationic mildness aids often co-precipitate with anionic surfactants which detracts from the performance of both the anionic surfactant and the cationic polymer, which in turn results in decreased lathering, cleaning, and skin conditioning. A further drawback is that cationic mildness aids are polymers and therefore are quite viscous which in turn presents difficulties in processing the formulations and achieving a uniform distribution of a mildness aid in the final formulation. Also, cationic polymeric aids typically have a broad molecular weight distribution--this makes the formulation of a cleanser more difficult because the polymer will not necessarily function as a mildness aid over the entire molecular weight range. Thus, a continuous need exists to improve personal washing compositions to deliver optimum mildness, cleaning, and processing ease.
Accordingly, it is an object of the present invention to provide a mild personal washing composition while avoiding the disadvantages of the prior art.
It is another object of the invention to provide personal washing compositions containing specific dendrimers as mildness agents.
It is still another object of the invention to provide a method of cleaning the skin while avoiding the harsh effects on the skin of an anionic surfactant or by washing the skin with the inventive composition.
These and other objects of the invention will become more apparent from the detailed description and examples that follow.